Introducing titanium hydride on porous transport layer for more energy efficient water electrolysis with proton exchange membrane

Abstract

An extensive oxidation of the Ti occurs during proton exchange membrane (PEM) water electrolysis, leading to an increase in the ohmic resistance of the electrolyzer cell (RΩ) and lowered energy efficiency. This issue is often addressed by coating the anode components with platinum group metals. Our previous results showed that acid etching of the porous transport layer (PTL) leading to Ti depassivation and formation of a surface hydride, is an effective way to decrease the RΩ. Here, we aim to minimise the RΩ by a novel surface treatment of the PTL by combining Ti hydride formation with subsequent Ir coating. The PTL treatment consists of three steps: acid etching, electrochemical hydridation and final coating with Ir. Electrolysers with the modified PTLs were operated for three weeks. Electrochemical impedance spectroscopy was used to evaluate the time evolution of the RΩ. In comparison with pristine Ti PTL coated with Ir, the PTL with the full treatment achieved an additional 12% reduction in RΩ, resulting in a 15% increase in current density at 2 V. Therefore, the developed PTL treatment minimises the ohmic losses in PEM water electrolyser caused by PTL oxidation and leads to more energy efficient hydrogen production.